A move to ban Hezbollah and make membership of it illegal in the UK has been deemed "irresponsible" by Iran's foreign ministry.
On Monday it was announced the group will become a proscribed institution in the UK, making being a member of or inviting support for it a criminal offence.
Until now only the military wing of the Lebanon-based group had been outlawed in Britain and not its political arm.
A report by the official IRNA news agency said Bahram Ghasemi, the ministry's spokesman, called the plan a "wrong move".
He said it will not serve stability and security in Lebanon and ignores the will of a "large portion" of the Lebanese people.
Iran is a key supporter of Hezbollah and Mr Ghasemi said the Lebanese people support Hezbollah which "defends the territorial integrity of Lebanon and fights terrorism".
The plans from the Government will see affiliation to the group punishable by up to ten years in prison.
The British ban came as the United States increased pressure on Hezbollah, placing several sets of sanctions on the group and its regional backer Iran.
Lebanon's Hezbollah group rejected the British government's move to ban it as a terrorist organisation and called it an "insult" to the Lebanese people, while saying it evidenced subservience to the United States.
Sajid Javid said the move came as it became difficult to differentiate between the military wing and the political party of the group,
Hezbollah is Arabic for Party of God and is a Shiite Muslim movement that emerged during the early 1980s to fight Israeli occupation of Lebanon.
It had financial backing from Iran and the group maintains a formidable military force that rivals the Lebanese army.
